InetSocketAddress


1   /*
2    * @(#)InetSocketAddress.java   1.22 05/11/17
3    *
4    * Copyright 2006 Sun Microsystems, Inc. All rights reserved.
5    * SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
6    */
7   package java.net;
8   
9   import java.io.ObjectInputStream  ;
10  import java.io.IOException  ;
11  import java.io.InvalidObjectException  ;
12  
13  /**
14   *
15   * This class implements an IP Socket Address (IP address + port number)
16   * It can also be a pair (hostname + port number), in which case an attempt
17   * will be made to resolve the hostname. If resolution fails then the address
18   * is said to be <I>unresolved</I> but can still be used on some circumstances
19   * like connecting through a proxy.
20   * <p>
21   * It provides an immutable object used by sockets for binding, connecting, or
22   * as returned values.
23   * <p>
24   * The <i>wildcard</i> is a special local IP address. It usually means "any"
25   * and can only be used for <code>bind</code> operations.
26   *
27   * @see java.net.Socket
28   * @see java.net.ServerSocket
29   * @since 1.4
30   */
31  public class InetSocketAddress extends SocketAddress   {
32      /* The hostname of the Socket Address
33       * @serial
34       */     
35      private String   hostname = null;
36      /* The IP address of the Socket Address
37       * @serial
38       */
39      private InetAddress   addr = null;
40      /* The port number of the Socket Address
41       * @serial
42       */   
43      private int port;
44  
45      private static final long serialVersionUID = 5076001401234631237L;
46      
47      private InetSocketAddress() {
48      }
49  
50      /**
51       * Creates a socket address where the IP address is the wildcard address
52       * and the port number a specified value.
53       * <p>
54       * A valid port value is between 0 and 65535.
55       * A port number of <code>zero</code> will let the system pick up an
56       * ephemeral port in a <code>bind</code> operation.
57       * <p>
58       * @param   port    The port number
59       * @throws IllegalArgumentException if the port parameter is outside the specified
60       * range of valid port values. 
61       */
62      public InetSocketAddress(int port) {
63      this(InetAddress.anyLocalAddress(), port);
64      }
65  
66      /**
67       *
68       * Creates a socket address from an IP address and a port number.
69       * <p>
70       * A valid port value is between 0 and 65535.
71       * A port number of <code>zero</code> will let the system pick up an
72       * ephemeral port in a <code>bind</code> operation.
73       * <P>
74       * A <code>null</code> address will assign the <i>wildcard</i> address.
75       * <p>
76       * @param   addr    The IP address
77       * @param   port    The port number
78       * @throws IllegalArgumentException if the port parameter is outside the specified
79       * range of valid port values.
80       */
81      public InetSocketAddress(InetAddress   addr, int port) {
82      if (port < 0 || port > 0xFFFF) {
83          throw new IllegalArgumentException  ("port out of range:" + port);
84      }
85      this.port = port;
86      if (addr == null)
87          this.addr = InetAddress.anyLocalAddress();
88      else
89          this.addr = addr;
90      }
91  
92      /**
93       *
94       * Creates a socket address from a hostname and a port number.
95       * <p>
96       * An attempt will be made to resolve the hostname into an InetAddress.
97       * If that attempt fails, the address will be flagged as <I>unresolved</I>.
98       * <p>
99       * If there is a security manager, its <code>checkConnect</code> method
100      * is called with the host name as its argument to check the permissiom
101      * to resolve it. This could result in a SecurityException.
102      * <P>
103      * A valid port value is between 0 and 65535.
104      * A port number of <code>zero</code> will let the system pick up an
105      * ephemeral port in a <code>bind</code> operation.
106      * <P>
107      * @param   hostname the Host name
108      * @param   port    The port number
109      * @throws IllegalArgumentException if the port parameter is outside the range
110      * of valid port values, or if the hostname parameter is <TT>null</TT>.
111      * @throws SecurityException if a security manager is present and
112      *               permission to resolve the host name is
113      *               denied.
114      * @see #isUnresolved()
115      */
116     public InetSocketAddress(String   hostname, int port) {
117     if (port < 0 || port > 0xFFFF) {
118         throw new IllegalArgumentException  ("port out of range:" + port);
119     }
120     if (hostname == null) {
121         throw new IllegalArgumentException  ("hostname can't be null");
122     }
123     try {
124         addr = InetAddress.getByName(hostname);
125     } catch(UnknownHostException   e) {
126         this.hostname = hostname;
127         addr = null;
128     }
129     this.port = port;
130     }
131 
132     /**
133      *
134      * Creates an unresolved socket address from a hostname and a port number.
135      * <p>
136      * No attempt will be made to resolve the hostname into an InetAddress.
137      * The address will be flagged as <I>unresolved</I>.
138      * <p>
139      * A valid port value is between 0 and 65535.
140      * A port number of <code>zero</code> will let the system pick up an
141      * ephemeral port in a <code>bind</code> operation.
142      * <P>
143      * @param   host    the Host name
144      * @param   port    The port number
145      * @throws IllegalArgumentException if the port parameter is outside
146      *                  the range of valid port values, or if the hostname
147      *                  parameter is <TT>null</TT>.
148      * @see #isUnresolved()
149      * @return  a <code>InetSocketAddress</code> representing the unresolved
150      *          socket address
151      * @since 1.5
152      */
153     public static InetSocketAddress   createUnresolved(String   host, int port) {
154     if (port < 0 || port > 0xFFFF) {
155         throw new IllegalArgumentException  ("port out of range:" + port);
156     }
157     if (host == null) {
158         throw new IllegalArgumentException  ("hostname can't be null");
159     }
160     InetSocketAddress   s = new InetSocketAddress  ();
161     s.port = port;
162     s.hostname = host;
163     s.addr = null;
164     return s;
165     }
166 
167     private void readObject(ObjectInputStream   s) 
168     throws IOException  , ClassNotFoundException   {
169     s.defaultReadObject();
170     
171     // Check that our invariants are satisfied
172     if (port < 0 || port > 0xFFFF) {
173         throw new InvalidObjectException  ("port out of range:" + port);
174     }
175     
176     if (hostname == null && addr == null) {
177         throw new InvalidObjectException  ("hostname and addr " + 
178                          "can't both be null");
179     }
180     }
181 
182     /**
183      * Gets the port number.
184      *
185      * @return the port number.
186      */
187     public final int getPort() {
188     return port;
189     }
190 
191     /**
192      * 
193      * Gets the <code>InetAddress</code>.
194      *
195      * @return the InetAdress or <code>null</code> if it is unresolved.
196      */
197     public final InetAddress   getAddress() {
198     return addr;
199     }
200 
201     /**
202      * Gets the <code>hostname</code>.
203      *
204      * @return  the hostname part of the address.
205      */
206     public final String   getHostName() {
207     if (hostname != null)
208         return hostname;
209     if (addr != null)
210         return addr.getHostName();
211     return null;
212     }
213 
214     /**
215      * Returns the hostname, or the String form of the address if it
216      * doesn't have a hostname (it was created using a litteral).
217      * This has the benefit of <b>not</b> attemptimg a reverse lookup.
218      *
219      * @return the hostname, or String representation of the address.
220      * @since 1.6
221      */
222     final String   getHostString() {
223     if (hostname != null)
224         return hostname;
225     if (addr != null) {
226         if (addr.hostName != null)
227         return addr.hostName;
228         else
229         return addr.getHostAddress();
230     }
231     return null;
232     }
233 
234     /**
235      * Checks whether the address has been resolved or not.
236      *
237      * @return <code>true</code> if the hostname couldn't be resolved into
238      *      an <code>InetAddress</code>.
239      */
240     public final boolean isUnresolved() {
241     return addr == null;
242     }
243 
244     /**
245      * Constructs a string representation of this InetSocketAddress.
246      * This String is constructed by calling toString() on the InetAddress
247      * and concatenating the port number (with a colon). If the address
248      * is unresolved then the part before the colon will only contain the hostname.
249      *
250      * @return  a string representation of this object.
251      */
252     public String   toString() {
253     if (isUnresolved()) {
254         return hostname + ":" + port;
255     } else {
256         return addr.toString() + ":" + port;
257     }
258     }
259 
260     /**
261      * Compares this object against the specified object.
262      * The result is <code>true</code> if and only if the argument is
263      * not <code>null</code> and it represents the same address as
264      * this object.
265      * <p>
266      * Two instances of <code>InetSocketAddress</code> represent the same
267      * address if both the InetAddresses (or hostnames if it is unresolved) and port
268      * numbers are equal.
269      * If both addresses are unresolved, then the hostname & the port number
270      * are compared.
271      *
272      * @param   obj   the object to compare against.
273      * @return  <code>true</code> if the objects are the same;
274      *          <code>false</code> otherwise.
275      * @see java.net.InetAddress#equals(java.lang.Object)
276      */
277     public final boolean equals(Object   obj) {
278     if (obj == null || !(obj instanceof InetSocketAddress  ))
279         return false;
280     InetSocketAddress   sockAddr = (InetSocketAddress  ) obj;
281     boolean sameIP = false;
282     if (this.addr != null)
283         sameIP = this.addr.equals(sockAddr.addr);
284     else if (this.hostname != null)
285         sameIP = (sockAddr.addr == null) &&
286         this.hostname.equals(sockAddr.hostname);
287     else
288         sameIP = (sockAddr.addr == null) && (sockAddr.hostname == null);
289     return sameIP && (this.port == sockAddr.port);
290     }
291 
292     /**
293      * Returns a hashcode for this socket address.
294      *
295      * @return  a hash code value for this socket address.
296      */
297     public final int hashCode() {
298     if (addr != null)
299         return addr.hashCode() + port;
300     if (hostname != null)
301         return hostname.hashCode() + port;
302     return port;
303     }
304 }
305
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